fix(repository): Move backend code into subdirectory

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/notes/utils.ts

@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import base32Encode from 'base32-encode';
+import { randomBytes } from 'crypto';
+
+import { Alias } from './alias.entity';
+import { Note } from './note.entity';
+
+/**
+ * Generate publicId for a note.
+ * This is a randomly generated 128-bit value encoded with base32-encode using the crockford variant and converted to lowercase.
+ */
+export function generatePublicId(): string {
+  const randomId = randomBytes(16);
+  return base32Encode(randomId, 'Crockford').toLowerCase();
+}
+
+/**
+ * Extract the primary alias from a aliases of a note
+ * @param {Note} note - the note from which the primary alias should be extracted
+ */
+export async function getPrimaryAlias(note: Note): Promise<string | undefined> {
+  const listWithPrimaryAlias = (await note.aliases).filter(
+    (alias: Alias) => alias.primary,
+  );
+  if (listWithPrimaryAlias.length !== 1) {
+    return undefined;
+  }
+  return listWithPrimaryAlias[0].name;
+}